Study of B̅ →Xuℓν̅ decays in BB̅ events tagged by a fully reconstructed B-meson decay and determination of |V[subscript ub]|
Name
Lees-2012-events tagged by a fully reconstructed B-meson decay and determination o.pdf
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Author(s)
Sciolla, Gabriella
Dujmic, Denis
Cowan, Ray F
Date Issued
August 2012
Journal
Physical Review D
Publisher
American Physical Society
Citation
Lees, J. et al. “Study of B̅ →Xuℓν̅ decays in BB̅ events tagged by a fully reconstructed B-meson decay and determination of |V[subscript ub]|.” Physical Review D 86.3 (2012). © 2012 American Physical Society
Version
Final published version
Abstract
We report measurements of partial branching fractions for inclusive charmless semileptonic B decays B̅ →Xuℓν̅ and the determination of the Cabibbo–Kobayashi–Maskawa (CKM) matrix element |Vub|. The analysis is based on a sample of 467×10[superscript 6] Υ(4S)→BB̅ decays recorded with the BABAR detector at the PEP-II e[superscript +]e[superscript -] storage rings. We select events in which the decay of one of the B mesons is fully reconstructed and an electron or a muon signals the semileptonic decay of the other B meson. We measure partial branching fractions ΔB in several restricted regions of phase space and determine the CKM element |V[subscript ub]| based on different QCD predictions. For decays with a charged lepton momentum p[subscript ℓ][superscript *]>1.0 GeV in the B meson rest frame, we obtain ΔB=(1.80±0.13[subscript stat]±0.15[subscript sys]±0.02[subscript theo])×10[superscript -3] from a fit to the two-dimensional M[subscript X]-q[superscript 2] distribution. Here, M[subscript X] refers to the invariant mass of the final state hadron X and q[superscript 2] is the invariant mass squared of the charged lepton and neutrino. From this measurement we extract |V[subscript ub]|=(4.33±0.24[subscript exp]±0.15[subscript theo])×10[superscript -3] as the arithmetic average of four results obtained from four different QCD predictions of the partial rate. We separately determine partial branching fractions for B̅[superscript 0] and B[superscript -] decays and derive a limit on the isospin breaking in B̅→X[subscript u]ℓν̅ decays.
MIT Department
Massachusetts Institute of Technology. Laboratory for Nuclear Science
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DOI of Published Version
https://doi.org/10.1103/PhysRevD.86.032004
